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Commit e1f6c07b authored by Kevin Coffman's avatar Kevin Coffman Committed by Trond Myklebust
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gss_krb5: add ability to have a keyed checksum (hmac) 



Encryption types besides DES may use a keyed checksum (hmac).
Modify the make_checksum() function to allow for a key
and take care of enctype-specific processing such as truncating
the resulting hash.

Signed-off-by: default avatarKevin Coffman <kwc@citi.umich.edu>
Signed-off-by: default avatarSteve Dickson <steved@redhat.com>
Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
parent 81d4a433

include/linux/sunrpc/gss_krb5.h

+8 −3
Original line number Diff line number Diff line
@@ -41,6 +41,9 @@ 
#include <linux/sunrpc/gss_err.h>

#include <linux/sunrpc/gss_asn1.h>



/* Maximum key length (in bytes) for the supported crypto algorithms*/

#define GSS_KRB5_MAX_KEYLEN (32)



/* Maximum checksum function output for the supported crypto algorithms */

#define GSS_KRB5_MAX_CKSUM_LEN  (20)
@@ -74,6 +77,7 @@ struct krb5_ctx { 
	const struct gss_krb5_enctype *gk5e; /* enctype-specific info */

	struct crypto_blkcipher	*enc;

	struct crypto_blkcipher	*seq;

	u8			cksum[GSS_KRB5_MAX_KEYLEN];

	s32			endtime;

	u32			seq_send;

	struct xdr_netobj	mech_used;
@@ -159,9 +163,10 @@ enum seal_alg { 
	+ GSS_KRB5_TOK_HDR_LEN                                   \

	+ GSS_KRB5_MAX_CKSUM_LEN)



s32

make_checksum(char *, char *header, int hdrlen, struct xdr_buf *body,

		   int body_offset, struct xdr_netobj *cksum);

u32

make_checksum(struct krb5_ctx *kctx, char *header, int hdrlen,

		struct xdr_buf *body, int body_offset, u8 *cksumkey,

		struct xdr_netobj *cksumout);



u32 gss_get_mic_kerberos(struct gss_ctx *, struct xdr_buf *,

		struct xdr_netobj *);

net/sunrpc/auth_gss/gss_krb5_crypto.c

+46 −8
Original line number Diff line number Diff line
@@ -123,21 +123,42 @@ checksummer(struct scatterlist *sg, void *data) 
	return crypto_hash_update(desc, sg, sg->length);

}



/* checksum the plaintext data and hdrlen bytes of the token header */

s32

make_checksum(char *cksumname, char *header, int hdrlen, struct xdr_buf *body,

		   int body_offset, struct xdr_netobj *cksum)

/*

 * checksum the plaintext data and hdrlen bytes of the token header

 * The checksum is performed over the first 8 bytes of the

 * gss token header and then over the data body

 */

u32

make_checksum(struct krb5_ctx *kctx, char *header, int hdrlen,

	      struct xdr_buf *body, int body_offset, u8 *cksumkey,

	      struct xdr_netobj *cksumout)

{

	struct hash_desc                desc; /* XXX add to ctx? */

	struct hash_desc                desc;

	struct scatterlist              sg[1];

	int err;

	u8 checksumdata[GSS_KRB5_MAX_CKSUM_LEN];

	unsigned int checksumlen;



	if (cksumout->len < kctx->gk5e->cksumlength) {

		dprintk("%s: checksum buffer length, %u, too small for %s\n",

			__func__, cksumout->len, kctx->gk5e->name);

		return GSS_S_FAILURE;

	}



	desc.tfm = crypto_alloc_hash(cksumname, 0, CRYPTO_ALG_ASYNC);

	desc.tfm = crypto_alloc_hash(kctx->gk5e->cksum_name, 0, CRYPTO_ALG_ASYNC);

	if (IS_ERR(desc.tfm))

		return GSS_S_FAILURE;

	cksum->len = crypto_hash_digestsize(desc.tfm);

	desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;



	checksumlen = crypto_hash_digestsize(desc.tfm);



	if (cksumkey != NULL) {

		err = crypto_hash_setkey(desc.tfm, cksumkey,

					 kctx->gk5e->keylength);

		if (err)

			goto out;

	}



	err = crypto_hash_init(&desc);

	if (err)

		goto out;
@@ -149,8 +170,25 @@ make_checksum(char *cksumname, char *header, int hdrlen, struct xdr_buf *body, 
			      checksummer, &desc);

	if (err)

		goto out;

	err = crypto_hash_final(&desc, cksum->data);

	err = crypto_hash_final(&desc, checksumdata);

	if (err)

		goto out;



	switch (kctx->gk5e->ctype) {

	case CKSUMTYPE_RSA_MD5:

		err = kctx->gk5e->encrypt(kctx->seq, NULL, checksumdata,

					  checksumdata, checksumlen);

		if (err)

			goto out;

		memcpy(cksumout->data,

		       checksumdata + checksumlen - kctx->gk5e->cksumlength,

		       kctx->gk5e->cksumlength);

		break;

	default:

		BUG();

		break;

	}

	cksumout->len = kctx->gk5e->cksumlength;

out:

	crypto_free_hash(desc.tfm);

	return err ? GSS_S_FAILURE : 0;

net/sunrpc/auth_gss/gss_krb5_mech.c

+1 −0
Original line number Diff line number Diff line
@@ -66,6 +66,7 @@ static const struct gss_krb5_enctype supported_gss_krb5_enctypes[] = { 
	  .keylength = 8,

	  .blocksize = 8,

	  .cksumlength = 8,

	  .keyed_cksum = 0,

	},

};

net/sunrpc/auth_gss/gss_krb5_seal.c

+7 −6
Original line number Diff line number Diff line
@@ -101,6 +101,7 @@ gss_get_mic_v1(struct krb5_ctx *ctx, struct xdr_buf *text, 
	void			*ptr;

	s32			now;

	u32			seq_send;

	u8			*cksumkey;



	dprintk("RPC:       %s\n", __func__);

	BUG_ON(ctx == NULL);
@@ -109,15 +110,15 @@ gss_get_mic_v1(struct krb5_ctx *ctx, struct xdr_buf *text, 


	ptr = setup_token(ctx, token);



	if (make_checksum((char *)ctx->gk5e->cksum_name, ptr, 8,

						text, 0, &md5cksum))

		return GSS_S_FAILURE;

	if (ctx->gk5e->keyed_cksum)

		cksumkey = ctx->cksum;

	else

		cksumkey = NULL;



	if (krb5_encrypt(ctx->seq, NULL, md5cksum.data,

			  md5cksum.data, md5cksum.len))

	if (make_checksum(ctx, ptr, 8, text, 0, cksumkey, &md5cksum))

		return GSS_S_FAILURE;



	memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data + md5cksum.len - 8, 8);

	memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data, md5cksum.len);



	spin_lock(&krb5_seq_lock);

	seq_send = ctx->seq_send++;

net/sunrpc/auth_gss/gss_krb5_unseal.c

+8 −5
Original line number Diff line number Diff line
@@ -84,6 +84,7 @@ gss_verify_mic_v1(struct krb5_ctx *ctx, 
	u32			seqnum;

	unsigned char		*ptr = (unsigned char *)read_token->data;

	int			bodysize;

	u8			*cksumkey;



	dprintk("RPC:       krb5_read_token\n");
@@ -108,14 +109,16 @@ gss_verify_mic_v1(struct krb5_ctx *ctx, 
	if ((ptr[6] != 0xff) || (ptr[7] != 0xff))

		return GSS_S_DEFECTIVE_TOKEN;



	if (make_checksum((char *)ctx->gk5e->cksum_name, ptr, 8,

					message_buffer, 0, &md5cksum))

		return GSS_S_FAILURE;

	if (ctx->gk5e->keyed_cksum)

		cksumkey = ctx->cksum;

	else

		cksumkey = NULL;



	if (krb5_encrypt(ctx->seq, NULL, md5cksum.data, md5cksum.data, 16))

	if (make_checksum(ctx, ptr, 8, message_buffer, 0,

			  cksumkey, &md5cksum))

		return GSS_S_FAILURE;



	if (memcmp(md5cksum.data + 8, ptr + GSS_KRB5_TOK_HDR_LEN,

	if (memcmp(md5cksum.data, ptr + GSS_KRB5_TOK_HDR_LEN,

					ctx->gk5e->cksumlength))

		return GSS_S_BAD_SIG;